What are the other Names for this Condition? (Also known as/Synonyms)

• 4-Alpha Aminobutyrate Transaminase Deficiency
• GABAT Deficiency
• Gamma Aminobutyrate Transaminase Deficiency

What is Gamma Aminobutyric Acid Transaminase Deficiency? (Definition/Background Information)

• GABA (gamma-aminobutyric acid) is an important molecule which slows down the activity of cells in the brain
• GABA is broken down in the body by a substance known as 4-aminobutyrate aminotransferase, also known as GABA-transaminase or GABA-T
• Mutations in the ABAT gene can cause less GABA-T to be made, a condition known as Gamma Aminobutyric Acid Transaminase Deficiency (GABA-T Deficiency)
• The symptoms for an individual with GABA-T Deficiency can include: psychomotor retardation (a slowing down of thought and activity), low muscle tone, hyperactive responses, lethargy, seizures, and EEG abnormalities
• GABA-T Deficiency is very rare, with fewer than 5 cases reported in the literature. It is thought to be inherited in an autosomal recessive manner

(Source: Gamma Aminobutyric Acid Transaminase Deficiency; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Who gets Gamma Aminobutyric Acid Transaminase Deficiency? (Age and Sex Distribution)

• Gamma Aminobutyric Acid Transaminase Deficiency is a rare congenital disorder. Less than 20 cases have been reported in the literature so far
• The presentation of symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Gamma Aminobutyric Acid Transaminase Deficiency? (Predisposing Factors)

• A positive family history may be an important risk factor, since Gamma Aminobutyric Acid Transaminase Deficiency can be inherited
• Currently, no other risk factors have been clearly identified for the disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Gamma Aminobutyric Acid Transaminase Deficiency? (Etiology)

• The cause of Gamma Aminobutyric Acid Transaminase Deficiency is due to genetic mutations involving the ABAT gene
• The condition is reportedly inherited in an autosomal recessive manner

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Gamma Aminobutyric Acid Transaminase Deficiency?

The symptoms for an individual with Gamma Aminobutyric Acid Transaminase Deficiency can include:

• Psychomotor retardation (a slowing down of thought and activity)
• Low muscle tone
• Hyperactive responses
• Lethargy
• Seizures
• EEG abnormalities

(Source: Gamma Aminobutyric Acid Transaminase Deficiency; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

How is Gamma Aminobutyric Acid Transaminase Deficiency Diagnosed?

Gamma Aminobutyric Acid Transaminase Deficiency is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Gamma Aminobutyric Acid Transaminase Deficiency?

The complications of Gamma Aminobutyric Acid Transaminase Deficiency may include:

• Brain-related abnormalities
• Intellectual impairment

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Gamma Aminobutyric Acid Transaminase Deficiency Treated?

There is no cure for Gamma Aminobutyric Acid Transaminase Deficiency, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complications that develops.

How can Gamma Aminobutyric Acid Transaminase Deficiency be Prevented?

Currently, Gamma Aminobutyric Acid Transaminase Deficiency may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Gamma Aminobutyric Acid Transaminase Deficiency? (Outcomes/Resolutions)

• The prognosis of Gamma Aminobutyric Acid Transaminase Deficiency is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Gamma Aminobutyric Acid Transaminase Deficiency:

Gamma Aminobutyric Acid Transaminase Deficiency is also known by the following names:

• GABA Transaminase Deficiency
• GABA-T Deficiency

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/